Tens of thousands of protesters streamed to a central Tel Aviv square after sundown Thursday, demanding the resignation of Prime Minister Ehud Olmert because of a scathing inquiry report about the way he ordered and handled last summer's bloody, costly but inconclusive war in Lebanon.

"Olmert you failed, you have been irresponsible to this nation," one demonstrator shouted.

Olmert remained defiant, hoping to beat back a rising wave of calls to step down. A day after his popular foreign minister, Tzipi Livni, joined the chorus, Olmert's aides felt she had not dealt him a mortal political blow. But they admitted that a large-scale public protest campaign could bring him down.

However, most other members of Olmert's Kadima party refused to follow the foreign minister's lead, reports CBS News correspondent Robert Berger. In fact only three of 29 Kadima lawmakers joined the attempted coup.

"Politicians are survivors. They fight for their career. I think it's especially true for Ehud Olmert. And I don't think that, given his past, he's the kind of person to give up," said analyst Avraham Diskin.

Thursday's turnout appeared to top 100,000, though police refused to estimate the crowd's size.

It was made up of a cross-section of Israelis — moderates and hard-liners, secular and religious, young and old, a rare mix symbolizing the widespread dissatisfaction with Olmert. Organizers claimed success, though it remained to be seen whether the outpouring of anger would be enough to oust the prime minister.

"Failures, Go Home!" read the banner behind the podium, where parents of soldiers killed in the conflict were to speak. Organizers decided not to allow politicians to address the crowd, to give the gathering a grass-roots nature, said Uzi Dayan, a retired general. "There are no politicians here, but this is a political event," he said.

Some political demonstrations in the past have attracted hundreds of thousands of protesters, and the size of this one was seen as a critical sign of the extent of public anger.

Edan Mehallel, 16, said he came to make a difference. "The more people there are, the more influence the demonstration will have," he said.

Past protests in the same Tel Aviv square have started political earthquakes. A demonstration there after Israel's disastrous 1973 war led to the resignation of legendary Prime Minister Golda Meir and Defense Minister Moshe Dayan.

Alon Davidi and 34 other protesters started marching 45 miles to Tel Aviv two days ago from the southern town of Sderot, a frequent target of rockets from Palestinian militants in Gaza.

"We want as many people as possible to come to the square and say, 'Ehud Olmert, go home,'" Davidi told Israel Army Radio.

Israel went to war against Hezbollah guerrillas in Lebanon on July 12 after guerrillas crossed into Israel, killed three soldiers and captured two others.

For many Israelis, the 34-day war was a failure because it didn't achieve the two main goals Olmert set — returning the soldiers and crushing Hezbollah, which fired nearly 4,000 rockets at northern Israel.

The conflict killed 158 Israelis and more than 1,000 Lebanese.

The Olmert-appointed commission to investigate the war turned on its creator, blasting Olmert for "hasty" decision-making, failure to consult others and neglecting to assess the chances that his goals could actually be accomplished.

The report covered only the first six days of the war and the six years that led up to it. The full report is expected in the summer — another benchmark in Olmert's political survival campaign.

Insiders in Olmert's Kadima Party said he has overcome the first onslaught. Kadima leaders rallied around their beleaguered chief Thursday, clearly mindful that a mutiny could lead to new elections that would hand power to hawkish former Prime Minister Benjamin Netanyahu, who is leading the polls.

Israel's parliament interrupted its spring recess on Thursday to hold a special session on the war report, where Netanyahu appealed for new elections.

"We must redress the primary flaw the report identifies — the lack of a seasoned leadership, the lack of responsibility, the inability to make tough decisions and carry them out," he told a sparsely attended session.

Olmert was present in the chamber, but did not speak.

Even if Olmert weathers the current crisis, two upcoming events are expected to pose even greater challenges to his rule: a party primary and a final report on the Lebanon war.

Olmert's main coalition partner, Labor, is scheduled to hold a May 28 primary election that is expected to oust Defense Minister Amir Peretz, a lesser target of the inquiry report. A new Labor leader may well decide to bolt the coalition, which almost certainly would deal a fatal blow to Olmert's government.

Even optimists doubt Olmert would be able to stay in power if the final Lebanon report is as harsh as the first one.

Also auguring poorly for Olmert's political survival is the history of protests at the plaza where Thursday's protest was held.

In 1982, hundreds of thousands marched to the square to protest Israel's involvement in the massacre of Palestinian refugees in Beirut by a Christian militia, a step toward the resignation of then-Defense Minister Ariel Sharon and the eventual retirement of Prime Minister Menachem Begin.

In 1995, after a peace rally, Prime Minister Yitzhak Rabin was assassinated in the square by an Israeli opponent of his policy of compromise for peace with the Palestinians. The square was renamed for the fallen leader.